Cool Season Grass and NPK ratios of 4:1:2 or 3:1:2 for heavy Fall ap....?

Discussion in 'Fertilizer Application' started by Exact Rototilling, Sep 3, 2013.

  1. Exact Rototilling

    Exact Rototilling LawnSite Fanatic
    Posts: 5,362

    ....and since polymer coated urea needs warmer temps I'm thinking mid September would be a good cut off date for this specific product for my zone.

  2. Skipster

    Skipster LawnSite Bronze Member
    Posts: 1,074

    The product you attached here looks fine, but instead of looking at the ratio of analysis nutrients, I would look at what your soil test values and what you've used for fertilizer earlier this year. What does your soil test tell you about P and K? If P and K aren't needed, you're just wasting money (and possibly polluting the environment) by applying them. You won't get a greener looking lawn by applying more P or K than what's needed.

    Also consider how much of each nutrient your lawns will need. The application recommendations on the fert bag are based off the N amount. The product you showed applies about 1#N/M according to the directions, which means that the 3-1-2 will apply about 1#N/M, 0.33# P2O5/M, and 0.67# K2O/M, while the 4-1-2 applied at 1# N/M will deliver about 0.25# P2O5/M and 0.5# K2O/M. If your program calls for 1# N/M and you need more P, the 3-1-2 will work out better for you. If you need more K, the 4-1-2 will work out better.

    The bottom line is that the analysis doesn't matter. The only thing that matters is how much nutrient do you need and how much do you apply. 3-1-2 vs 4-1-2? If your soil tests have adequate P and/or K, neither of those are your best options.
  3. RigglePLC

    RigglePLC LawnSite Fanatic
    Posts: 12,235

    Good points Skipster. Exact doesn't need the phosphorus--maybe K is adequate, also. Remember K has nothing to do with green color. What does your typical soil test indicate in your area?

    Polymer-coated urea does not depend on bacteria for nitrogen release. It should release fine in cool weather. And besides, when you read the fine print--the mixture only contains 3 percent slow release nitrogen. Or 1.5 pounds in the bag.
    When you read the bottom line it looks like they claim 15 percent slow-release.
    They are basing their claim on the idea that 15 percent of the nitrogen is slow release. 3.1 over 21 is 14.67 percent of nitrogen as slow-release. This is a bit misleading unless you read and compare labels carefully.
    Last edited: Sep 3, 2013
  4. foreplease

    foreplease LawnSite Bronze Member
    Posts: 1,940

    I respect what you've both said as good practices. The fact is though that not all of Exact's lawns are going to have the same lab results, nevermind that none of us can test every lawn every year. In addition to the suggestions you've made, I suggest considering several other factors - beginning with what are the available products or combinations of products available in your area. I know that is a little backwards but short of custom blending it needs to be considered.

    Other considerations include: what is known about the history of the lawn, underlying soil type, amount of precipitation or other water compared to other years, is K being mined out of the yard by bagging clippings, is the lawn being mowed properly and frequently enough (minimal self-inflected injuries), amount of shade, dsirable species present, will the fertilizer under consideration contribute to (or help) any pH problem the lawn has, if any.

    On my invoices I have a section about what to expect and another for what needs to be done next. Obviously then I believe it is important to keep what is next in mind while I am doing what is today. And customer expectations: what do they want and expect and what have you promised them

    In response to the original question, I dearly miss having a season long target of 4:1:2 here. I can't prove why and I can't swear things are any worse, but the advice we were given at MSU is soils classes was to start with 4:1:2 or 4:1:3 and adjust. We are too close to when we lost P to now yet what difference, if any, it has made in turf.

    I can be more flexible than people who do lawns. All mine get tested usually before I start the first year and at 2-3 year intervals thereafter. P and K levels rarely come back as needing attention or a change for me. Micros and pH are occasional issues. Soil texture and OM (separate test) sometimes need attention. Almost everyone here sees more different customers in a day than I see In an entire season. None of my places are on the same program although many have similar goals.
  5. DA Quality Lawn & YS

    DA Quality Lawn & YS LawnSite Fanatic
    Posts: 8,900

    Not much of that N come from slow release poly coat. Do you want to run that type of fert now or perhaps wait until cooler temps and consistent rainfall prevail?

    I am running 100% slow N right now, on irrigated lawns and lawns that do not show too much drought stress. As we move toward fall, cooler temps, and hopefully some rainfall, I want to switch over to a greater mineral source of N so that the N is rapidly available for plants to use as they rebuild themselves from summer stress.

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